On Sat, Jul 28, 2018 at 5:56 AM, Saravana Kannan <skannan@xxxxxxxxxxxxxx> wrote: > Many CPU architectures have caches that can scale independent of the CPUs. > Frequency scaling of the caches is necessary to make sure the cache is not > a performance bottleneck that leads to poor performance and power. The same > idea applies for RAM/DDR. > > To achieve this, this patch adds a generic devfreq governor that can listen > to the frequency transitions of each CPU frequency domain and then adjusts > the frequency of the cache (or any devfreq device) based on the frequency > of the CPUs. > > To decide the frequency of the device, the governor does one of the > following: > > * Uses a CPU frequency to device frequency mapping table > - Either one mapping table used for all CPU freq policies (typically used > for system with homogeneous cores/clusters that have the same OPPs. > - One mapping table per CPU freq policy (typically used for ASMP systems > with heterogeneous CPUs with different OPPs) > > OR > > * Scales the device frequency in proportion to the CPU frequency. So, if > the CPUs are running at their max frequency, the device runs at its max > frequency. If the CPUs are running at their min frequency, the device > runs at its min frequency. And interpolated for frequencies in between. While not having looked at the details of the patch yet, I would change the name of the feature to "Generic cpufreq transition governor" to make it somewhat less ambiguous. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
